fix missing scene3d files

src/dlangui/graphics/scene/drawableobject.d

@@ -0,0 +1,15 @@
+module dlangui.graphics.scene.drawableobject;
+
+public import dlangui.core.types;
+public import dlangui.graphics.scene.node;
+
+/// Reference counted DrawableObject
+alias DrawableObjectRef = Ref!DrawableObject;
+
+class DrawableObject : RefCountedObject {
+    this() {
+    }
+    void draw(Node3d node, bool wireframe) {
+        /// override it
+    }
+}

src/dlangui/graphics/scene/model.d

@@ -0,0 +1,28 @@
+module dlangui.graphics.scene.model;
+
+import dlangui.graphics.scene.drawableobject;
+import dlangui.graphics.scene.mesh;
+import dlangui.graphics.scene.material;
+
+class Model : DrawableObject {
+    protected MaterialRef _material;
+    protected MeshRef _mesh;
+
+    this() {
+    }
+
+    this(Material material, Mesh mesh) {
+        _material = material;
+        _mesh = mesh;
+    }
+
+    @property ref MaterialRef material() { return _material; }
+    @property ref MeshRef mesh() { return _mesh; }
+
+    override void draw(Node3d node, bool wireframe) {
+        /// override it
+        _material.bind(node);
+        _material.drawMesh(_mesh);
+        _material.unbind();
+    }
+}